Research Review #2
Maybe you check your smartwatch like it’s handing out grades.
Close all three rings? Excellent work. Miss one? Now a tiny computer on your wrist seems disappointed in you.
Fitness trackers can count steps, measure heart rate, estimate calories, score your sleep, and remind you to stand up. But the useful question is whether wearing one actually changes your health or behavior.
A large research review recently looked for an answer.
What the researchers wanted to know
The researchers reviewed 39 previous reviews covering 98 studies. Ninety-five were randomized controlled trials, meaning people were assigned to different groups so researchers could compare the results.
Every study used a wrist-worn tracker that gave people feedback as part of an effort to improve their health. Fitbit was the most common device, but the research also included Polar, Garmin, ActiGraph, Jawbone, and other trackers.
There’s an important catch: More than 80 percent of the studies combined the tracker with something else, such as coaching, goal setting, or group support.
More than half of the comparison groups also received a lifestyle program—just without the tracker.
So most studies compared a program plus a tracker with a similar program without a tracker.
Trackers helped people move more
The clearest improvements involved physical activity.
| Outcome | Group | Effect |
|---|---|---|
| Daily steps | Adults with overweight or obesity | Moderate |
| Daily steps | Older adults | Large |
| Total physical activity | Cancer survivors | Moderate |
| Moderate-to-vigorous activity | Older adults | Large |
| Sedentary time | Cancer survivors | Moderate decrease |
The researchers reported these results using standardized mean differences, or SMDs. As a rough guide, 0.2 is considered a small effect, 0.5 moderate, and 0.8 large. The effects above ranged from 0.62 to 0.97, with sedentary time decreasing by 0.72.
Those are meaningful changes for something as stubborn as human behavior.
Most health markers barely changed
The trackers did much less for the health measurements people often hope to improve.
Across the studies, they did not produce significant improvements in body weight, HbA1c, systolic blood pressure, or blood lipids.
HbA1c reflects your average blood sugar over the previous few months. Blood lipids include cholesterol and triglycerides.
The results for quality of life, depression, anxiety, and pain were limited and inconsistent.
People with cardiovascular disease were one exception. Their exercise capacity improved modestly. Their fasting blood sugar and diastolic blood pressure also improved, although the evidence for those changes was less certain.
Why more movement didn’t always mean better numbers
Behavior can change faster than physiology.
If you add 2,000 steps tomorrow, your tracker will record the difference immediately. Changes in blood pressure, cholesterol, blood sugar, or body weight may take longer—and may depend on many other factors.
A lot of the studies were short. More than a third were pilot or feasibility studies designed to test whether a larger study would be practical. They may not have lasted long enough to capture slower health changes.
Long-term research does link higher step counts with better health. One meta-analysis found that every additional 1,000 daily steps was associated with a 12 percent lower risk of death from any cause.
That association does not prove the extra steps caused the entire reduction. It does support the broader idea that regular movement matters.
Don’t give the watch too much credit
Most people in these studies weren’t simply handed a tracker and sent on their way. They also received goals, coaching, education, or social support.
The research suggests that a tracker can make those efforts more effective. It does not show that buying a smartwatch automatically improves your health.
A tracker gives you information. You still need a realistic goal and some idea of what to do with the data.
A practical way to use your tracker
Choose one measurement that connects to a behavior you actually want to change.
- Use your step count to gradually increase daily walking.
- Look at weekly averages instead of judging individual days.
- Notice which parts of your routine keep you sitting for long stretches.
- Use the data to spot patterns, not to chase perfection.
- Review your results with a coach or healthcare professional when you need help choosing an appropriate target.
The tracker is most useful when its information helps you make a decision.
Know when tracking is working against you
For some people, tracking becomes stressful.
You may start treating every number as a judgment. A missed goal feels like failure. Resting becomes something you have to justify. You ignore how you feel because the device says you’re “ready.”
If that sounds familiar, try tracking fewer measurements, checking the app less often, or taking a break from the device. Your watch can provide useful information, but it doesn’t understand your entire life—and it definitely doesn’t get a vote on your worth as a person.
Bottom line
Fitness trackers can help you move more, particularly when you use them with a clear goal and some support.
They are much less likely to transform your weight, blood pressure, blood sugar, cholesterol, or mental health by themselves.
Use the device as a feedback tool. Give the numbers a purpose, keep them in perspective, and remember who is supposed to be in charge.
References
Glisic M, Llane A, Stojic S, Llanaj E, Roa-Díaz ZM, Raguindin PF, et al. An umbrella review of systematic reviews of the impact of wrist-worn wearables on health outcomes. Physiological Reviews. 2026;106(2):935–969.
Jayedi A, Gohari A, Shab-Bidar S. Daily step count and all-cause mortality: A dose-response meta-analysis of prospective cohort studies. Sports Medicine. 2022;52(1):89–99.